the extension now crashes Firefox using gmail Rated 4 out of 5 stars

This is a new issue, because google mail just changed something (only in the English version for now). If you are using gmail (set to English) and the extension is enabled, you click on "Sent mail" and Firefox crashes completely under Windows that is.
Otherwise I like the extension.

This review is for a previous version of the add-on (0.8.4.0).